1. Field of the Invention
The present invention relates generally to backlight modules and, in particular, to backlight modules using light emitting diodes (LED) as light sources and providing backlight for liquid crystal display (LCD) devices.
2. Description of Related Art
For typical design of LED backlight modules, a single-side design has long been adopted, meaning that all the LED components and other electronic components, including LED drivers and passive components, are mounted on the same side of the circuit board. To handle the problem caused by heat dissipation of the LED components, a metal core printed circuit board (MCPCB) has been used as the circuit board in conventional technology. The aluminum layer at the bottom of the MCPCB can serve a similar purpose as a heat sink and discharge the heat generated by the electronic components, especially the LED components.
Such single-side designs, however, have a problem caused by those electronic components that are of a greater height than the LED components. An optical reflector for diffusing emitted light normally has to be kept at an optimal distance from the LED components to give a satisfactory light diffusion effect. The optimal distance is usually less than the maximum height of those electronic components, and therefore the reflector has to be molded into irregular shape instead of a smooth planar structure. Consequently, uniform backlight cannot be provided because of the irregular shape of the reflector. Further, extra manufacturing costs are incurred for an irregularly shaped reflector.
Accordingly, a need exists for improved methods and apparatuses of backlighting that adopt smooth planar reflectors.